Systems for satin finishing pipes by means of flap wheels—that is by means of wheels comprising a plurality of radial flaps (normally) fixed by gluing to a hub—have long been known and are used with good results since, with respect to the systems of the prior art, they allow a better surface finish of the pipe and a higher production rate.
The flap wheels currently available on the market have not allowed the above-mentioned flap-wheel satin finishing systems to fully realize their potential since it has been found experimentally that during the satin finishing of a pipe (also because of the heat that develops by friction between the flaps and the surface to be satin finished) the temperature of the wheel (and in particular of its hub) reaches such high values (a temperature of 120-150° C. has been measured at the hub) as to (be able to) cause a physical alteration in the components used to produce the flap wheel, degrading in particular the mechanical binding and cohesive characteristics of the material (normally a resin) used as adhesive to fix the flaps to the hub.
This fact, together with the high speed of the wheel (which can have a peripheral speed of 30-35 m/s), means that the material used as adhesive loses (or can lose) its ability to retain the flaps in place, overcoming the centrifugal force acting on said flaps: it has in fact been found experimentally that the flaps gradually become detached from the wheel hub and consequently the life of the wheel, its ability to effectively remove the material from the surface to be processed and the safety of the operators are reduced, unless the wheel is placed beneath a sufficiently robust cover.
The object of the present invention is to produce a flap wheel, in particular a flap wheel for satin finishing systems for pipes or for sheet metal, that is free from the drawbacks and from the limitations of the flap wheels currently known to the art.
In the appended figures corresponding elements will be denoted by the same reference numerals.